查詢每個部門中薪資最高的員工
阿新 • • 發佈：2019-01-04
The Employee table holds all employees. Every employee has an Id, a salary, and there
is also a column for the department Id.
+----+-------+--------+--------------+ | Id | Name | Salary | DepartmentId | +----+-------+--------+--------------+ | 1 | Joe | 70000 | 1 | | 2 | Henry | 80000 | 2 | | 3 | Sam | 60000 | 2 | | 4 | Max | 90000 | 1 | +----+-------+--------+--------------+
The Department table holds all departments of the company.
+----+----------+ | Id | Name | +----+----------+ | 1 | IT | | 2 | Sales | +----+----------+
Write a SQL query to find employees who have the highest salary in each of the departments. For the above tables, Max has the highest salary in the IT department and Henry has the highest salary in the Sales department.
+------------+----------+--------+ | Department | Employee | Salary | +------------+----------+--------+ | IT | Max | 90000 | | Sales | Henry | 80000 | +------------+----------+--------+第一欠考慮的情況：
select Department.Name as Department,Employee.name as Employee ,max(Employee.Salary) as Salary from Employee join Department on Employee.DepartmentId=Department.Id group by Employee.DepartmentId;
（這種情況只能顯示部門只有一個薪資最高的情況，如果有多個人薪資同時達到最高，就只顯示一個）
正解：
SELECT dep.Name as Department, emp.Name as Employee, emp.Salary
from Department dep, Employee emp
where emp.DepartmentId=dep.Id
and emp.Salary=(Select max(Salary) from Employee e2 where e2.DepartmentId=dep.Id)